Vehicles equipped with an automatic or semi-automatic transmission typically include a transmission control means remotely located from the transmission to permit the operator of the vehicle to select the desired directional mode or an assigned range of speed reductions. These transmission control means are well known in the art and commerically available in many forms. See, for example, U.S. Pat. Nos. 3,470,771 and 3,350,957.
Generally, a conventional, remotely located, transmission control means includes an operator movable lever pivotably mounted to a housing for operating a mechanical linkage such as a push-pull cable or rigid connecting rod and/or bellcrank between the lever and the transmission. Juxtapositioned at the point at which the movable lever passes through the housing is an open gating arrangement (commonly referred to as gate plate) through which the lever must a move. The gate plate is normally of prescribed length and includes various "shift stations" which are positions or points along the plate that correspond to the shifting point of the transmission or operational mode thereof. A typical gate plate includes a stepped or incremental arrangement so that movement of the control lever requires additional and similar planar action to move it from one shift station to another. In such cases, the lever is biased against the steps of the gate plate. The stepping arrangement of the gate plate in conjunction with the biased lever provides a safety feature in that unintentional movement of the control lever to a different shift station is minimized because of the secondary positive action in the same plane but diverse directions, required to move the lever against the steps.
Notwithstanding the use of stepped gate plates and the like, it has become desirable in many applications to have a positive lock-out or interlock feature which prevents movement of the control lever in any of a number of pre-selected directions without simultaneously requiring another action in a distinctly different plane to occur. The lock-out features of conventional control means are typically designed to operate separately from the gate plate. Because these lock-out or interlocking devices are separate and apart from the gating arrangement, they require additional parts which are subject to increased wear and manufacturing costs.
In a conventional transmission control where the movable lever is pivotably positioned in the housing to pass through an opening therein the operator is subjected to noise which is transmitted into the housing from the transmission and through the opening into the vehicle cab. To overcome this problem, numerous supplemental devices such as split seals, slide seals, rubber boots, diaphrams, and the like have been used in an attempt to seal the interior of the housing from the operator. Most of these attempts have been unsatisfactory because of the high cost of the seal and/or its premature failure under severe operation or extreme environmental conditions to which most controls are subjected.
It is, therefore, an object of the present invention to provide a rugged transmission control means having a minimum number of parts which also includes a positive lock-out mechanism integral with the lever control and the shift station gating mechanism. It is also an object of the invention to provide a novel gating means which permits the adjacent pivotal surfaces of the lever to simultaneously act as a unique seal and wiper to substantially reduce noise levels and maintain air temperature differential internal of the housing from reaching the operator and, conversely, to prevent any foreign substance or the like from entering into the control housing. It is a further object of the invention to provide a control means having a reduced size without sacrificing the strength and accuracy of the control. It is also an object of the invention to provide within the reduced size of the control a unique direct-reading indicator of control lever positioning, so as to completely free the operator from the judgment or from distinquishing between chromatic colors or operating within extreme light level conditions were prior art indicators are not adequate. Accordingly, the present invention overcomes many of the problems and disadvantages inherent in prior art devices.